Technical Details

For heartbeats input:

Arduino Duemilanove 328

" The Arduino Duemilanove ("2009") is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

"Duemilanove" means 2009 in Italian and is named after the year of its release. The Duemilanove is the latest in a series of USB Arduino boards; for a comparison with previous versions, see the index of Arduino boards. "

IR emitters & detectors

"Side-looking Infrared Emitters and IR Detectors. These simple devices operate at 940nm and work well for generic IR systems including remote control and touch-less object sensing. Using a simple ADC on any microcontroller will allow variable readings to be collected from the detector. The emitter is driven up to 50mA with a current limiting resistor as with any LED device. The detect is a NPN transistor that is biased by incoming IR light." Get it here

Resistors

10 k ohm and 270 ohm

Amplifier

To amplify and strengthen the signals from the heartbeats

Projector

How the sensor works:

Refer and image from Meng Li.